The invention relates to a control apparatus for driving a laser diode, in particular an electronic circuit for guaranteeing product safety in vehicle lighting installations having a laser diode. Furthermore, the invention relates to a lighting apparatus for a vehicle and a vehicle having a lighting apparatus of this kind.
Laser diodes are increasingly replacing light sources previously used in vehicle headlamps, such as for example light emitting diodes (LEDs), xenon bulbs or filament bulbs. The control units used for conventional illuminants are not suitable for the electrical driving of laser diodes. The electrical and thermal characteristics of semiconductor lasers require control electronics and control logic designed especially for them. For driving purposes, laser diodes necessarily require an upstream electronics unit which takes into account the specific characteristics of this illuminant in order to be able to guarantee a correct and high-quality reproduction of the light functions to be reproduced thereby under the operating conditions prevailing in the vehicle over the lifetime. The new kinds of laser diodes cannot be operated in the vehicle for lighting purposes or be integrated into the on-board vehicle power supply without automotive-qualified control electronics.
Because of the laser radiation present in the system, which can cause severe injuries in the event of an uncontrolled escape, active measures are necessary for ensuring the safety of the product under all operating conditions and fault occurrences. Particularly for the use of light sources which are subject to a laser class classification >1, additional measures are necessary in order to prevent danger to human beings and other creatures due to unintentionally escaping laser radiation.
It is desirable to specify a control apparatus for driving a laser diode, with which it is made possible to operate the laser diode safely and reliably. Furthermore, a lighting apparatus for a vehicle, with which it is made possible to operate a laser diode safely and reliably, is to be specified. Further, a vehicle having a lighting apparatus of this kind is to be specified.
An embodiment of a control apparatus comprises an output connection for connecting the laser diode, a regulation device for generating an output signal at a connection of the regulation device, a detector device which is designed to determine a regulation variable when the regulation device provides the output signal at the connection and the laser diode is connected to the output connection of the control apparatus. Furthermore, the control apparatus comprises a computer device for providing a control signal for the regulation device. The computer device provides the control signal independently of the regulation variable. The regulation device is designed in such a way that it generates a level for the output signal depending on the control signal and the determined regulation variable.
An embodiment of an illumination apparatus for a vehicle comprises a laser diode and a control apparatus for driving the laser diode according to the embodiment specified above. The laser diode is connected to the output connection of the control apparatus.
A regulated driving of laser diodes in vehicle illumination installations can be ensured by means of the specified control apparatus. In doing so, brightness, color temperature and temperature can be controlled. Specific characteristics of laser diodes, for example different brightness classes, can be matched to desired target values. The life of the laser diodes can be controlled by means of electrical and thermal limitation, thus enabling them to be designed for the vehicle life.
The specified control apparatus is also suitable without limitation for the operation of conventional, that is to say spontaneously emitting, LEDs. This enables hybrid headlamps with laser diodes and light emitting diodes to be driven and diagnosed. Some lighting functions in the automotive sector are subject to a functional safety classification (ASIL level). The development process, in particular the hardware and software development, must therefore generally be carried out in accordance with a standard, for example in accordance with ISO 26262.
The invention is explained in more detail below with reference to figures which show exemplary embodiments of the present invention. In the drawings:
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.